A hot-rolled AZ31 Mg alloy sheet was subjected to dynamic plastic deformation parallel to the rolling direction with the aim of introducing {10-12} twins. Subsequent tensile tests were carried out along the predeformed direction and the initial transverse direction (TD). It was found that untwinning led to a significant drop in yield stress when tension is carried out along the predeformed direction. And {10-12} twins and strain caused by twinning were recovered by untwinning. The tensile yield stress increased slightly with prestrain was correlated with the texture hardening caused by untwinning. When tension is carried out along initial TD, {10-12} twinning activity was restrained and slip dominated plastic deformation. The tensile yield stress increased significantly with prestrain was strongly correlated with the hardening contributions of {10-12} twins. {10-12} twinning led to the obvious yield stress in-plane anisotropy but had little effect on the maximum flow stress.